Surface treating appliances such as floor sweepers and vacuum cleaners may be provided with a cleaner head which includes a rotatable agitator for improving the cleaning performance of the appliance. FIG. 1 shows such a cleaner head by way of an example. The cleaner head 1 comprises a housing 2 in which is mounted an agitator 3, a drive assembly 4 and a control assembly 5.
The agitator 3 comprises an elongate agitator body 6 one end of which is mounted to a bush 8 and seated in a removable cap 9, and the other end of which is mounted to a transmission 11 that forms part of the drive assembly 4. The agitator is therefore journalled between the transmission 11 and the bush 8 so that it can be rotated by the transmission 11. In a known manner the transmission is driven by an electric motor 10.
Referring to the agitator 3 in more detail, the elongate body 6 of the agitator 3 carries a plurality of bristle strips 7. Each bristle strip 7 comprises a ribbon-like carrier to which a plurality of bristles or filaments are attached so as to extend away perpendicularly from the carrier. Note that the individual bristles cannot be seen in FIG. 1. Each of the bristle strips is secured in a track defined by the agitator body 6 in a helical formation. The use of bristle strips in agitators is advantageous since they provide an efficient way to install a relatively dense and uniform row of bristles or filaments to an agitator. This type of agitator may be referred to in the art by various terms; beater bar or brush bar, for example and such terms should be considered synonymous.
The bristle strips extend from one end of the agitator to the other end and terminate at bearing portions. One end of the agitator is shown in detail in FIG. 2 and it can be seen here that the perpendicular bristles do not extend right to the end of the agitator but instead terminate at the bearing portion 6a. This configuration leaves a margin at each end of the cleaner head that is not processed by the agitator in use and so dust and debris may remain adhered to the floor surface in these margins. This can be a problem when using the cleaner head to clean up to an edge of a room since dirt may remain in a margin along the edge of the room. As a general principle, therefore, it is desirable to maximize the ‘swept width’ of an agitator within a cleaner head.